1. Field of the Invention
This invention relates generally to the fabrication of hollow metal balls for use in rolling contact bearings and other applications.
2. Description of the Prior Art
In various industrial applications where extensive use is made of ball bearings and where total equipment weight is a significant factor, the use of hollow ball hearings has been found highly beneficial. For example, in modern military and passenger aircraft, the use of hollow ball bearings in engine construction can yield weight reductions of several hundred pounds.
During high speed operation, substantial inertial forces are exerted upon the bearing races which rotatively secure the ball bearings. The bearing races effectuate smooth movement of the bearing balls in the race during rotational movement with respect to a shaft or journal. The greater weight of solid balls in comparison to hollow balls increases the inertia and centrifugal force of the bearing system, thereby diminishing its anti-frictional mission.
Methods for manufacturing hollow ball bearings generally involve the joinder of a pair of half-shell elements in the form of hemispheres, said joinder being achieved by a butt-joint arrangement utilizing a welding or diffusion bonding technique. With such bonding methods, however, an excessive amount of material generally called a "flash" or "bead" is deposited both inside and outside of the joint area. While the excess of flash material on the outside surface of the joint may be rather easily removed, that formed on the inside surface thereof, of course, remains. The internal flash produces stress of the metallic microstructure, promotes a nonuniform stiffening, and creates unbalanced and consequent unstable conditions in the bearing during its operation. In addition, such welded, or diffusion-bonded joints have proven to be relatively weak, and, therefore, comparatively unreliable. The processes for achieving joinder by the aforesaid techniques are complicated in that they require precise alignment not only of the two hemispheres, but also of the bonding material and/or its means of application.
It is accordingly an object of the present invention to provide a process for the production of hollow ball bearings of improved balance and uniformity.
It is another object of this invention to provide a process as in the foregoing object which is more easily amenable to precision operation.
It is a further object of the present invention to provide a process of the aforesaid nature which affords reduced manufacturing costs.
These objects and other objects and advantages of the invention will be apparent from the following description.